Physical hemodynamic interaction between portal venous and hepatic arterial blood flow in humans

Comparison of portal vein hemodynamics with ultrasound-based elastography for the prediction of liver fibrosis in patients with chronic liver disease

Chronic liver disease includes nonalcoholic fatty liver disease, progresses from steatosis and hepatitis to fibrosis and cirrhosis, with hemodynamic changes in portal blood flow. This study aimed to compare portal vein hemodynamics with liver stiffness (LS) and steatosis and included 28 subjects with chronic liver disease, in whom LS and steatosis were evaluated in the same image employing two elastography techniques: transient elastography (TE) with controlled attenuation parameter (CAP) using a FibroScan and two-dimensional shear-wave elastography (2D-SWE) with attenuation imaging (ATI). Additionally, peak maximum velocity (V_max) of the right portal vein and spleen stiffness with 2D-SWE were evaluated. A strong positive correlation was present between LS values obtained with TE and 2D-SWE and between the attenuation coefficients of steatosis obtained with CAP and ATI. Additionally, a negative correlation was present between LS values and the V_max of the right portal vein (r = 0.415, p = 0.031). The optimal V_max cutoff value for discriminating liver fibrosis with an LS value of > 5 kPa was < 17 cm/s; the ability of V_max to predict fibrosis was comparable to that of the FIB4-index. Low V_max of the right portal vein was useful for identifying liver fibrosis in patients with chronic liver disease.

A comparative study between arterial spin labeling and CT perfusion methods on hepatic portal venous flow

PURPOSE

The purpose of this study was to evaluate the feasibility and potential usefulness of unenhanced magnetic resonance (MR) hepatic portal perfusion using arterial spin labeling (ASL) among healthy volunteers and hepatocellular carcinoma patients.

MATERIALS AND METHODS

The five healthy volunteers underwent unenhanced MR perfusion with inversion time 2 (TI2) values at 500-ms intervals between 2,000 and 4,000 ms, and the 12 patients underwent unenhanced MR perfusion using ASL and computed tomography (CT) perfusion during superior mesenteric artery (SMA) portography. The regions of interest were placed in both the right and left lobes of the liver or both the right anterior and posterior segments of the liver and were placed over the tumor if a lesion was located within a particular perfusion study slice.

RESULTS

In the healthy volunteer study, perfusion rate in hepatic parenchyma showed a peak at the TI2 value of 3,000 ms (254.3 ml/min/100 g ± 58.3). In patients, a fair correlation was observed between CT and MR perfusion (r = 0.795, P < 0.01).

CONCLUSION

Our results demonstrate a significant fair correlation between unenhanced MR hepatic portal perfusion imaging using ASL and CT perfusion during SMA portography.

Ultrasound assessment of short-term ocular vascular effects of intravitreal injection of bevacizumab (Avastin(®) ) in neovascular age-related macular degeneration

PURPOSE

Angiogenic inhibitors, alone or combined with other therapies, are believed to represent a promising treatment for neovascularization in age-related macular degeneration (wet AMD). They can maintain or improve visual acuity (VA), at least for the first 2years. However, evolution to retinal atrophy cannot be ruled out and it may be useful to assess the effects of antiangiogenic therapy on retinal and choroidal circulation.

METHODS

We carried out a pilot study in 15 patients with wet AMD. Time-averaged mean blood flow velocities (BFVs) in the central retinal, temporal posterior ciliary and ophthalmic arteries (CRA, TPCA and OA) were measured by ultrasound imaging before and 4weeks after a single intravitreal injection of 1.25mg bevacizumab in 0.05ml. Patients underwent two ophthalmic examinations, before and 4weeks after injection, including VA measurement and optical coherence tomography (OCT3) examination.

RESULTS

  In treated eyes, bevacizumab injection was followed by a significant improvement in VA (from 20/125 to 20/80; p=0.0214), and a decrease in mean central macular thickness (from 392±96μm to 271±50μm; p=0.0038). Mean BFV decreased by 10% in the CRA (p=0.0226), 20% in the TPCA (p=0.0026) and 20% in the OA (p=0.0003). No effect was observed in fellow eyes.

CONCLUSIONS

  Intravitreal bevacizumab acutely improved VA and reduced central macular thickness in wet AMD. Ultrasound imaging revealed that BFVs decreased in all retrobulbar arteries, suggesting that after local diffusion, bevacizumab exerts a short-term regional effect. Bevacizumab might therefore induce hypoperfusion of the whole eye, which may correspond to a vascular side-effect.

Liver abscess after common hepatic artery embolization for delayed hemorrhage following pancreaticoduodenectomy: a case report

A 55-year-old man underwent pancreaticoduodenectomy for bile duct carcinoma in March 2009. The patient developed anastomotic leakage and had a short episode of hemorrhage from the drainage tubes with spontaneous disappearance. CT and upper endoscopy did not reveal the source of bleeding. A massive life-threatening hemorrhage occurred on the 18th postsurgical day. Emergency angiography showed a 2.7-cm pseudoaneurysm of the gastroduodenal artery stump, and hepatic artery embolization was performed. After embolization, an abscess appeared in segments 2/3 of the liver without involving the right lobe. We treated conservatively by drainage and antibiotics. During the course of therapy after embolization, the patient experienced several episodes of high fever but did not develop hepatic failure. On the 68th day after embolization, the abscess had penetrated to the lesser sac, which was immediately treated by percutaneous drainage. Anastomotic leakage was treated by continuous irrigation from the drain, for which complete resolution was achieved by the 34th day after embolization. The patient was discharged 101 days after embolization. Imaging and the clinical course demonstrate a unique mechanism of abscess formation after embolization.

Angiotensinogen delays angiogenesis and tumor growth of hepatocarcinoma in transgenic mice

Angiotensinogen, a member of the serpin family, is involved in the suppression of tumor growth and metastasis. To investigate whether human angiotensinogen protects against tumor progression in vivo, we established an original bitransgenic model in which transgenic mice expressing human angiotensinogen (Hu-AGT-TG mice) were crossed with a transgenic mouse model of hepatocellular carcinoma (HCC-TG mice). Bitransgenic mice overexpressing human angiotensinogen (HCC/Hu-AGT-TG) had a significantly longer survival time than the HCC-TG mice and a reduction of both tumor growth and blood flow velocities in the liver. This antitumor effect of angiotensinogen is related to a reduced angiogenesis, impaired expression of endothelial arterial markers (active Notch4, Delta-like 4 ligand, and ephrin B2) with a decrease of arterial vessel density in HCC/Hu-AGT-TG mice liver. Overexpression of human angiotensinogen decreases angiogenesis, and prevents tumor sinusoids from remodeling and arterialization, thus delaying tumor progression in vivo.

Ultrasonic assessment of hepatic blood flow as a marker of mouse hepatocarcinoma

Two-dimensional color-coded pulsed Doppler ultrasonography (US) with a 12-MHz linear transducer was used to follow tumor growth and neoangiogenesis development in 12 transgenic mice developing a whole liver hepatocellular carcinoma (HCC) induced by the expression of SV40-T antigen. In this model, male mice developed HCC at various temporal and histologic stages (hyperplastic, four-eight wk; nodular, 12 wk; diffuse carcinoma, 16-20 wk), whereas female mice remained tumor free. Seven age-matched tumor-free mice were used as controls. Liver volume was calculated from B-mode images of the abdomen. Blood flow waveforms were recorded from the hepatic tumor-feeding artery upstream from the tumor vessels, allowing quantitative blood flow velocity measurements. Measurements were performed every four weeks from four to 20 weeks. As early as the hyperplastic stage (eight weeks), liver volume was increased by 2.7-fold, hepatic artery peak-systolic blood flow velocities (BFV) by 1.5-fold, end-diastolic BFV by 1.6-fold and mean BFV by 2.0-fold compared with control values (p < 0.001). Differences increased until 20 weeks and peak-systolic reached 90 +/- 6, end-diastolic 54 +/- 5 and mean BFV 48 +/- 5 cm s(-1). Successive measurements of BFV were reproducible and intraobserver repeatability coefficient values were <3 cm s(-1). In contrast, mesenteric artery BFV, which did not supply tumor region, did not show any significant difference with respect to control values. Thus, an increase in BFV constitutes a functional evaluation of tumor vascularity. In preclinical studies in small animals, measurements of liver volume and blood flow velocities in hepatic tumor-feeding artery provide a useful, reproducible, noninvasive, easy-to-repeat tool to monitor tumor growth and neoangiogenesis in hepatocellular carcinoma in mice.

Normal Hepatic Hemodynamics During Early Postoperative Period in Recipients With Adult Live Donor Liver Transplantation

To recognize "normal" hepatic hemodynamics after live donor liver transplantation (LDLT), we analyzed Doppler parameters on recipients with a right liver graft and donors after extended left hepatectomy. Theoretically these values should be the same. From April 2000 to October 2004, 20 LDLTs were performed using a right liver graft. The 10 recipients without postoperative complications and their donors were included in this study. Portal venous velocity (PVV; cm/s), hepatic arterial peak systolic velocity (cm/s), and hepatic venous peak velocity (HVPV; cm/s) were measured during the first 2 weeks. In donors PVV and HVPV after LDLT were significantly higher after than before left hepatectomy: 19.2 +/- 4.2 vs. 31.5 +/- 13.0 cm/s (P = .013) and 23.0 +/- 7.2 vs. 41.8 +/- 10.3 cm/s respectively (P = .010). However, there were mild degrees of increased PVV and HVPV. In recipients, a markedly increased PVV (106.3 +/- 45.2 cm/s on day 1) was significantly higher than that in donors on each postoperative day. The hepatic arterial resistive index in recipients was also significantly higher than that in donors on each postoperative day, for example, 0.72 +/- 0.11 vs 0.62 +/- 0.04 on day 1 (P = .0326). In conclusion, we have shown "abnormal" hepatic hemodynamics in even those recipients without complications during the early postoperative period after LDLT.